Liver fibrosis in chronic hepatitis C virus infection: differentiating minimal from intermediate fibrosis with perfusion CT

Liver function estimation using multiphase hepatic CT: diagnostic performance of iodine-uptake and volumetric parameters

OBJECTIVES

To investigate whether multiphase hepatic CT can predict liver function measured with indocyanine-green-retention test (ICG-R15) and identify patients with severe liver dysfunction contraindicating major hepatectomy, defined as ICG-R15 ≥ 20%, compared to technetium-99m-galactosyl serum albumin (99mTc-GSA) scintigraphy.

MATERIALS AND METHODS

This retrospective study included 118 patients (84 men, mean age, 69.4 ± 11.3 years) who underwent ICG-R15, 99mTc-GSA, and multi-phase CT including early portal-venous-phase and 3-min delayed-phase. CT-derived extracellular volume fraction (ECV), iodine washout rate (IWR), liver and spleen volumes normalized by body-surface-area (LV/BSA and SpV/BSA, respectively), and 99mTc-GSA-derived blood clearance index (HH15) and liver receptor index (LHL15) were quantified. Each parameter was compared between ICG-R15 ≥ 20% (n = 22) and ICG-R15 < 20% (n = 96) groups. Correlations with ICG-R15 were analyzed. The diagnostic performance to predict ICG-R15 ≥ 20% was assessed with areas under the receiver operating characteristic curve (AUC). Multivariable logistic regression analysis was used to identify independent CT predictors, and combined performance was determined.

RESULTS

In the ICG-R15 ≥ 20% group, IWR (p < 0.001), LV/BSA (p = 0.026), LHL15 (p < 0.001) were lower and ECV (p = 0.001), SpV/BSA (p = 0.005), and HH15 (p < 0.001) were higher compared to ICG-R15 < 20% group. ICG-R15 showed positive correlations with ECV (r = 0.355), SpV/BSA (r = 0.248), and HH15 (r = 0.385), while negative correlations with IWR (r = -0.523), LV/BSA (r = -0.123, not statistically significant), and LHL15 (r = -0.504). The AUC of ECV, IWR, LV/BSA, SpV/BSA, HH15, and LHL15 were 0.719, 0.845, 0.653, 0.694, 0.844, and 0.878, respectively. IWR, SpV/BSA, and LV/BSA were independent predictors, with a combined AUC of 0.924.

CONCLUSION

IWR predicted liver function better than ECV and hepatosplenic volumetry. The combined IWR and volumetry yielded an accurate prediction of severe liver dysfunction.

KEY POINTS

Question Despite the widespread use of multiphase CT in patients with hepatobiliary diseases, its potential role in assessing liver function has been scarcely evaluated. Findings Iodine washout rate (IWR), liver volume indexed by body surface area, and spleen volume indexed by body surface area were independent predictors for severe liver dysfunction. Clinical relevance Combined IWR and hepatosplenic volumetry on routine hepatic CT may help assess hepatic function for optimizing treatment strategies and predicting patient prognosis.

Noninvasive Quantitative CT for Diffuse Liver Diseases: Steatosis, Iron Overload, and Fibrosis

Chronic diffuse liver disease continues to increase in prevalence and represents a global health concern. Noninvasive detection and quantification of hepatic steatosis, iron overload, and fibrosis are critical, especially given the many relative disadvantages and potential risks of invasive liver biopsy. Although MRI techniques have emerged as the preferred reference standard for quantification of liver fat, iron, and fibrosis, CT can play an important role in opportunistic detection of unsuspected disease and is performed at much higher volumes. For hepatic steatosis, noncontrast CT provides a close approximation to MRI-based proton-density fat fraction (PDFF) quantification, with liver attenuation values less than or equal to 40 HU signifying at least moderate steatosis. Liver fat quantification with postcontrast CT is less precise but can generally provide categorical assessment (eg, mild vs moderate steatosis). Noncontrast CT can also trigger appropriate assessment for iron overload when increased parenchymal attenuation values are observed (eg, >75 HU). A variety of morphologic and functional CT features indicate the presence of underlying hepatic fibrosis and cirrhosis. Beyond subjective assessment, quantitative CT methods for staging fibrosis can provide comparable performance to that of elastography. Furthermore, quantitative CT assessment can be performed retrospectively, since prospective techniques are not required. Many of these CT quantitative measures are now fully automated via artificial intelligence (AI) deep learning algorithms. These retrospective and automated advantages have important implications for longitudinal clinical care and research. Ultimately, regardless of the indication for CT, opportunistic detection of steatosis, iron overload, and fibrosis can result in appropriate clinical awareness and management. ©RSNA, 2024 See the invited commentary by Yeh in this issue.

Ferulic acid ameliorates concanavalin A-induced hepatic fibrosis in mice via suppressing TGF-β/smad signaling

BACKGROUND AND AIM

Hepatic fibrosis, one of the main reasons for death globally, is a serious complication of chronic liver disorders. However, the available therapies for liver fibrosis are limited, ineffective, and often associated with adverse events. Hence, seeking for a novel, effective therapy is warranted. Our objective was to investigate the potential efficacy of ferulic acid (FA), a phenolic phytochemical, at different doses in hindering the progress of concanavalin A (Con A)-induced hepatic fibrosis and explore the involved mechanisms.

METHODS

Thirty-six mice were assorted into 6 groups (n = 6): Group I (control); group II received FA (20 mg/kg/day orally for 4 weeks); group III received Con A (6 mg/kg/week/i.v.) for 4 weeks; groups IV, V, and VI received Con A and were offered FA at 5, 10, and 20 mg/kg/day, respectively.

RESULTS

The data showed the palliative effect of FA against Con A-induced fibrosis in a dose-dependent manner. This was obvious from the recovery of liver markers and hepatic architecture with the regression of fibrosis in FA-treated mice. FA abolished Con A-mediated oxidative insults and promoted the antioxidant enzyme activities, which run through the Nrf2/HO-1 signaling. Additionally, FA suppressed Con A-induced increase in NF-kB and IL-β levels, and TNF-α immune-expression. The anti-fibrotic effect of FA was evident from the drop in TGF-β, smad3 levels, α-SMA expression, and hydroxyproline content.

CONCLUSION

FA attenuated Con A-induced liver fibrosis through stimulating Nrf2 signaling, suppressing NF-kB, and inhibiting the TGF-β/smad3 signaling pathway. Thus FA can be considered as a promising therapy for combating liver fibrosis.

Advancements of non‐invasive imaging technologies for the diagnosis and staging of liver fibrosis: Present and future

Liver fibrosis is a reparative response triggered by liver injury. Non‐invasive assessment and staging of liver fibrosis in patients with chronic liver disease are of paramount importance, as treatment strategies and prognoses depend significantly on the degree of fibrosis. Although liver fibrosis has traditionally been staged through invasive liver biopsy, this method is prone to sampling errors, particularly when biopsy sizes are inadequate. Consequently, there is an urgent clinical need for an alternative to biopsy, one that ensures precise, sensitive, and non‐invasive diagnosis and staging of liver fibrosis. Non‐invasive imaging assessments have assumed a pivotal role in clinical practice, enjoying growing popularity and acceptance due to their potential for diagnosing, staging, and monitoring liver fibrosis. In this comprehensive review, we first delved into the current landscape of non‐invasive imaging technologies, assessing their accuracy and the transformative impact they have had on the diagnosis and management of liver fibrosis in both clinical practice and animal models. Additionally, we provided an in‐depth exploration of recent advancements in ultrasound imaging, computed tomography imaging, magnetic resonance imaging, nuclear medicine imaging, radiomics, and artificial intelligence within the field of liver fibrosis research. We summarized the key concepts, advantages, limitations, and diagnostic performance of each technique. Finally, we discussed the challenges associated with clinical implementation and offer our perspective on advancing the field, hoping to provide alternative directions for the future research.

Conventional and artificial intelligence-based computed tomography and magnetic resonance imaging quantitative techniques for non-invasive liver fibrosis staging

Chronic liver disease (CLD) ultimately develops into liver fibrosis and cirrhosis and is a major public health problem globally. The assessment of liver fibrosis is important for patients with CLD for prognostication, treatment decisions, and surveillance. Liver biopsies are traditionally performed to determine the stage of liver fibrosis. However, the risks of complications and technical limitations restrict their application to screening and sequential monitoring in clinical practice. CT and MRI are essential for evaluating cirrhosis-associated complications in patients with CLD, and several non-invasive methods based on them have been proposed. Artificial intelligence (AI) techniques have also been applied to stage liver fibrosis. This review aimed to explore the values of conventional and AI-based CT and MRI quantitative techniques for non-invasive liver fibrosis staging and summarized their diagnostic performance, advantages, and limitations.

Noninvasive staging of liver fibrosis: review of current quantitative CT and MRI-based techniques

Liver fibrosis features excessive protein accumulation in the liver interstitial space resulting from repeated tissue injury due to chronic liver disease. Liver fibrosis eventually proceeds to cirrhosis and associated complications. So, early diagnosis and staging of liver fibrosis are of vital importance for clinical treatment. Liver biopsy remains the gold standard for the diagnosing and staging of fibrosis, but it is suboptimal due to various limitations. Recently, efforts have been made to migrate toward noninvasive techniques for assessing liver fibrosis. CT is relatively easy to perform, relatively standardized for different scanners, and does not require additional hardware in liver fibrosis staging. MRI is frequently performed to characterize indeterminate liver lesions. Because it does not use ionizing radiation and features high image contrast, its role has increased in the staging of liver fibrosis. More recently, several studies on liver fibrosis staging using deep learning algorithms in CT or MRI have been proposed and have shown meaningful results. In this review, we summarize the basic concept, diagnostic performance, and advantages and limitations of each technique to noninvasively stage liver fibrosis.

Evaluation of perfusion CT and dual-energy CT for predicting microvascular invasion of hepatocellular carcinoma

PURPOSE

Evaluation of perfusion CT and dual-energy CT (DECT) quantitative parameters for predicting microvascular invasion (MVI) of hepatocellular carcinoma (HCC) prior to surgery.

METHODS

This prospective single-center study included fifty-six patients (44 men; median age 67; range 31-84) who provided written informed consent. Inclusion criteria were (1) treatment-naïve patients with a diagnosis of HCC, (2) an indication for hepatic resection, and (3) available arterial DECT phase and perfusion CT (GE revolution HD-GSI). Iodine concentrations (IC), arterial density (AD), and 9 quantitative perfusion parameters for HCC were correlated to pathological results. Radiological parameters based principal component analysis (PCA), corroborated by unsupervised heatmap classification, was meant to deliver a model for predicting MVI in HCC. Survival analysis was performed using univariable log-rank test and multivariable Cox model, both censored at time of relapse.

RESULTS

58 HCC lesions were analyzed (median size 42.3 mm; range of 20-140). PCA showed that the radiological model was predictive of tumor grade (p = 0.01), intratumoral MVI (p = 0.004), peritumoral MVI (p = 0.04), MTM (macrotrabecular-massive) subtype (p = 0.02), and capsular invasion (p = 0.02) in HCC. Heatmap classification of HCC showed tumor heterogeneity, stratified into three main clusters according to the risk of relapse. Survival analysis confirmed that permeability surface-area product (PS) was the only significant independent parameter, among all quantitative tumoral CT parameters, for predicting a risk of relapse (Cox p value = 0.004).

CONCLUSION

A perfusion CT and DECT-based quantitative imaging profile can provide a diagnosis of histological MVI in HCC. PS is an independent parameter for relapse.

CLINICAL TRIALS

ClinicalTrials.gov: NCT03754192.

Estimation of Contrast Agent Concentration in DCE-MRI Using 2 Flip Angles

PURPOSE

The aim of this study was to investigate the feasibility of using 2 flip angles (FAs) with an ultrashort echo time during dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) for estimation of plasma gadolinium (Gd) concentration without using a precontrast longitudinal relaxation time T1 (T10) measurement.

METHODS

T1-weighted DCE-MRI experiments were carried out with C57BL/6J mice using the scan protocol with 2 FAs over 3 sequential segments during 1 scan. The data with 2 FAs were used to estimate T10 (T1T) during conversion of a time-intensity curve to the time-concentration curve. Three dosages of gadolinium-based contrast agent were used to achieve a wide range of variability in Gd concentrations when measured at 10 minutes postinjection: 0.05 mmol/kg (n = 6), 0.1 mmol/kg (n = 11), and 0.15 mmol/kg (n = 7). For comparison, the signal-to-concentration conversion was also conducted using the T10 measured from the precontrast scan (T1M) as well as a constant T10 (2.1 seconds) from the literature (T1C). The Gd concentrations ([Gd]) estimated using DCE-MRI data for the time of retro-orbital blood collection ([Gd]T1T, [Gd]T1M, and [Gd]T1C, respectively) were compared against the [Gd] of the blood samples measured by inductively coupled plasma mass spectrometry ([Gd]MS). In addition, contrast kinetic model analysis was conducted on mice with GL261 brain tumors (n = 5) using the 3 different methods for T10.

RESULTS

T1T strongly correlated with T1M (r = 0.81). [Gd]T1M and [Gd]T1T were significantly different from [Gd]T1C. [Gd]T1M and [Gd]T1T were in good agreement with [Gd]MS with strong correlations (mean percentage error ± standard deviation) of r = 0.70 (16% ± 56%) and r = 0.85 (15% ± 44%), respectively. In contrast, [Gd]T1C had a weak correlation of r = 0.52 with larger errors of 33% ± 24%. The contrast kinetic model parameters of GL261 brain tumors using T1T were not significantly different from those using T1M.

CONCLUSIONS

This study substantiates the feasibility of using the 2-FA approach during DCE-MRI scan to estimate [Gd] in the plasma without using an extra scan to perform precontrast T1 measurements.

Comparing shear wave elastography with liver biopsy in the assessment of liver fibrosis at King Hussein Medical Center

Background and study aims

The aim of this prospective study is to compare the sensitivity and specificity of the liver shear wave elastography to the golden standard liver biopsy in staging liver fibrosis.

Patients and methods

Ninety-five patients were included in this study. These patients were sent for liver biopsy as a possible living liver donor or because of different pathologies including viral and autoimmune hepatitis and congenital liver diseases. A shear wave elastography and US-guided liver biopsy were done at the same setting by one experienced radiologist. One experienced histopathologist, blinded to SWE results, read the specimens.

Results

We included 95 patients in the study with a mean age of 30 years (range 3–65 years). We had 15/95 (16%) patients with hepatitis B/C, 61/95 (64%) patients with another liver disease, and 19/95 (20%) were donors. The mean of liver stiffness measured by elastography in patients was 6.5±0.19 kPa. The mean liver stiffness measured by elastography in patients with F0–F1 fibrosis was 5.39 ± 0.62 kPa, F2 was 7.32 ± 0.41, at stage F3 was 8.46 ± 0.33, and in the F4 stage, it was 11.42 ± 2.8 kPa. We found a significant difference in the mean level of liver stiffness in different degrees of fibrosis (p = 0.0001).

Conclusion

The shear wave elastography could be used to assess liver fibrosis regardless of the cause.

Advances and insights in the diagnosis of viral infections

Viral infections are the most common among diseases that globally require around 60 percent of medical care. However, in the heat of the pandemic, there was a lack of medical equipment and inpatient facilities to provide all patients with viral infections. The detection of viral infections is possible in three general ways such as (i) direct virus detection, which is performed immediately 1-3 days after the infection, (ii) determination of antibodies against some virus proteins mainly observed during/after virus incubation period, (iii) detection of virus-induced disease when specific tissue changes in the organism. This review surveys some global pandemics from 1889 to 2020, virus types, which induced these pandemics, and symptoms of some viral diseases. Non-analytical methods such as radiology and microscopy also are overviewed. This review overlooks molecular analysis methods such as nucleic acid amplification, antibody-antigen complex determination, CRISPR-Cas system-based viral genome determination methods. Methods widely used in the certificated diagnostic laboratory for SARS-CoV-2, Influenza A, B, C, HIV, and other viruses during a viral pandemic are outlined. A comprehensive overview of molecular analytical methods has shown that the assay's sensitivity, accuracy, and suitability for virus detection depends on the choice of the number of regions in the viral open reading frame (ORF) genome sequence and the validity of the selected analytical method.

Usefulness of diffusion derived vessel density computed from a simplified IVIM imaging protocol: An experimental study with rat biliary duct blockage induced liver fibrosis

OBJECTIVES

Liver vessel density can be evaluated by DDVD (diffusion derived vessel density): DDVD_(b0b1) = Sb0/ROIarea0 - Sb1/ROIarea1, where Sb0 and Sb1 refer to the liver signal when b is 0 or 1 s/mm². Sb1 and ROIarea1 may be replaced by other b-values. With a rat biliary duct ligation (BDL) model, this study assesses the usefulness of liver DDVD computed from a simplified IVIM imaging protocol using b = 25 and b = 50 to replace b = 1 s/mm², alone and in combination with other IVIM parameters.

METHODS

Male Sprague-Dawley rats were used. The rat number was 5, 5, 5, and 3 respectively, for the timepoints of 7, 14, 21, 28 days post-BDL surgery. 12 rats had partial biliary duct recanalization performed after the rats had BDL for 7 days and then again followed-up for a mean of 14 days. Liver diffusion MRIs were acquired at 3.0 T with a b-value distribution of 0, 25, 50, 75, 100, 150, 300, 700, 1000 s/mm². DDVD_mean (control rats n = 6) was the mean of DDVD_(b0b25) and DDVD_(b0b50). IVIM fitting started from b = 0 s/mm² with segmented fitting and a threshold b of 50 s/mm² (n = 5 for control rats). Three 3-D spaces were constructed using a combination of the four diffusion parameters.

RESULTS

The control rats and BDL rats (n = 18) had a liver DDVD_mean of 84.0 ± 26.2 and 44.7 ± 14.4 au/pixel (p < 0.001). All 3-D spaces totally separated healthy livers and all fibrotic livers (n = 30, BDL rats and recanalization rats). The mean relative distance between healthy liver cluster and fibrotic liver cluster was 0.331 for PF, D_slow, and D_fast; 0.381 for PF, D_fast, and DDVD_mean; and 0.384 for PF, D_slow, and DDVD_mean.

CONCLUSION

A combination of PF, D_slow, and D_fast allows total separation of healthy livers and fibrotic livers and the integration of DDVD improved the separation.

Liver fibrosis assessment with multiphasic dual-energy CT: diagnostic performance of iodine uptake parameters

OBJECTIVES

To evaluate the ability of iodine uptake parameters from hepatic multiphasic CT to predict liver fibrosis, and compare absolute contrast enhancement (ΔHU) with dual-energy iodine density (ID) methods.

METHODS

One hundred seventeen patients with pathologically proven liver fibrosis who underwent dual-energy CT during portal-venous phase (PVP) and 3-min delayed phase (DP) between January 2017 and Octotber 2019 were retrospectively included. Two radiologists measured the hepatic and blood-pool iodine uptake using ΔHU and ID methods; extracellular volume fraction (ECV) and the iodine washout rate (IWR) calculated with both methods were compared between different fibrosis stages (F0-1 vs. F2-4, F0-2 vs. F3-4, or F0-3 vs. F4). The inter-observer reproducibility (intraclass correlation coefficients [ICCs]) for ECV and IWR was compared between the ΔHU and ID methods. The areas under the receiver operating characteristic curves (AUCs) to predict liver fibrosis severity were calculated for serum and imaging fibrosis markers. To identify independent predictors, multivariable logistic regression analysis was performed, and combined performance was assessed for the ΔHU and ID models.

RESULTS

Patients with F ≥ 2 (n = 70), F ≥ 3 (n = 51), and F4 (n = 29) had higher ECV and lower IWR than those with F ≤ 1, F ≤ 2, and F ≤ 3, respectively (all p < 0.001). ICCs were higher in the ID method than in the ΔHU method (ECV: p = 0.045; IWR: p < 0.001). The AUC ranges of ECV_ΔHU, ECV_ID, IWR_ΔHU, and IWR_ID for predicting liver fibrosis severity were 0.65-0.71, 0.67-0.73, 0.76-0.81, and 0.81-0.85, respectively. IWR and fibrosis-4 index were independent predictors, with combined AUCs of 0.82-0.87 for the ΔHU model and 0.86-0.89 for the ID model.

CONCLUSIONS

IWR more accurately predicted liver fibrosis than ECV in routine multiphasic CT. The dual-energy ID method yielded higher inter-observer reproducibility and predictive values than the single-energy ΔHU method.

KEY POINTS

• The IWR calculated from hepatic iodine uptake during PVP and 3-min DP predicted liver fibrosis (AUC, 0.76-0.85), while the ECV had a relatively limited predictive value (ACU, 0.65-0.73). • Compared with the conventional ΔHU method, the dual-energy ID method provided superior inter-observer reproducibility for measurement of ECV (p = 0.046) and IWR (p < 0.001). • The IWR and FIB-4 served as independent predictors of liver fibrosis; their combination yielded the high diagnostic performance particularly when using the ID method (combined AUCs of 0.86-0.89).

CT and MR perfusion techniques to assess diffuse liver disease

Perfusion imaging allows for the quantitative extraction of physiological perfusion parameters of the liver microcirculation at levels far below the spatial the resolution of CT and MR imaging. Because of its peculiar structure and architecture, perfusion imaging is more challenging in the liver than in other organs. Indeed, the liver is a mobile organ and significantly deforms with respiratory motion. Moreover, it has a dual vascular supply and the sinusoidal capillaries are fenestrated in the normal liver. Using extracellular contrast agents, perfusion imaging has shown its ability to discriminate patients with various stages of liver fibrosis. The recent introduction of hepatobiliary contrast agents enables quantification of both the liver perfusion and the hepatocyte transport function using advanced perfusion models. The purpose of this review article is to describe the characteristics of liver perfusion imaging to assess chronic liver disease, with a special focus on CT and MR imaging.

Noninvasive Tests (NITs) for Hepatic Fibrosis in Fatty Liver Syndrome

Fatty liver syndrome is an emerging health problem in the world, due to the high prevalence of obesity and alcohol use disorder. Given the nature of the disease's advancement to cirrhosis and liver-related complications, it is important to assess the severity of the disease, which is typically done via a liver biopsy. Due to the limitations and risks of liver biopsy, the role of noninvasive tests is essential and evolving to stratify the stage of the liver disease, predict the outcomes, and/or monitor the treatment response. This review is focused on noninvasive tests, including the use of serum-based biomarkers, ultrasound-based shear wave elastography, transient elastography, and magnetic resonance elastography in both clinical and research settings.

Predictive value of perfusion CT for blood loss in liver resection

Blood loss is associated with the degree of damage in liver stiffness. Severe liver steatosis is a matter of concern in liver surgery, but does not correlate with liver stiffness. This study aimed to assess the relationship between blood perfusion of the liver and blood loss in liver pathologies. Data from elective liver resection for liver cancer were analyzed. All patients underwent preoperative assessments including perfusion CT. Patients were divided into 4 groups in accordance with the pathological background of liver parenchyma. Relationships between portal flow as assessed by perfusion CT and perioperative variables were compared. Factors correlating with blood loss were analyzed. In 166 patients, portal flow from perfusion CT correlated positively with platelet count and negatively with indocyanine green retention rate at 15 min. Background liver pathology was normal liver (NL) in 43 cases, chronic hepatitis (CH) in 56, liver cirrhosis (LC) in 42, and liver steatosis (LS) in 25. Rates of hepatitis viral infection and pathological hepatocellular carcinoma were more frequent in LC and CH groups than in the other groups (p < 0.05). LC and LS showed significantly worse liver function than the NL and CH groups. Portal flow from perfusion CT correlated positively with damage to liver parenchyma and negatively with blood loss at liver transection. Low portal flow on perfusion CT predicts blood loss during liver transection.

Differentiating mild and substantial hepatic fibrosis from healthy controls: a comparison of diffusion kurtosis imaging and conventional diffusion-weighted imaging

BACKGROUND

Early and accurate detection of liver fibrosis are important for clinical treatment.

PURPOSE

To compare the diagnostic accuracy of liver diffusion kurtosis imaging (DKI) and conventional diffusion-weighted imaging (cDWI) in differentiating patients with mild and substantial fibrosis from normal individuals.

MATERIAL AND METHODS

Twenty-seven healthy volunteers with no fibrosis (S0) and 45 patients with mild (S1) or substantial (S2) liver fibrosis underwent DWI with multiple b-values. Liver mean apparent diffusion (MD) and mean kurtosis (MK) values derived from DKI and apparent diffusion coefficient (ADC) derived from cDWI were measured and compared. Their discriminative abilities were analyzed and compared by receiver operating characteristic (ROC) curve analysis.

RESULTS

Significant differences in MD and ADC values were found between groups (P < 0.05). MD value was statistically different between S0 and S1 (P = 0.028) and S0 and S2 (P = 0.005). ADC value was statistically different between S0 and S2 (P = 0.012). MK value was similar between groups (P = 0.646). MD and ADC values significantly correlated with fibrosis stages (r_s = -0.668, -0.341; P < 0.01). MK values had no correlation with fibrosis stages (r_s = 0.180; P = 0.130). The area under ROC curves (AUC) for MD and ADC was 0.937 and 0.707 for characterization of S1-2 and 0.817 and 0.658 for S2, respectively. MD performed better than ADC for characterization of S1-2 and S2 (P < 0.05).

CONCLUSION

Differentiating patients with mild or substantial fibrosis from normal individuals is feasible using DKI, which performs better than cDWI.

Non-invasive diagnosis of liver fibrosis: A review of current imaging modalities

Hundreds of millions of patients are suffering from cirrhosis and other chronic liver diseases worldwide, and this public health problem continues to grow. It has been proven that liver fibrosis is reversible after the elimination of the etiology, especially in the early stage. Thus, early diagnosis of liver fibrosis is of vital importance for clinical treatment. Liver biopsy remains the gold standard for both diagnosis and staging of fibrosis, but is suboptimal, due in large parts to its invasive nature and sundry associated complications. To overcome this, a number of non-invasive diagnosis based on serum biomarkers or imaging modalities have been developed. While diagnosis based on serum biomarkers is cheaper and more acceptable to patients, almost none developed to date are liver-specific, and may engender a false positive error. The imaging modalities have evolved rapidly and are taking on more and more important roles in the diagnosis of liver fibrosis.

Liver injury monitoring, fibrosis staging and inflammation grading using T1rho magnetic resonance imaging: an experimental study in rats with carbon tetrachloride intoxication

Background

To investigate the merit of T1rho relaxation for the evaluation of liver fibrosis, inflammatory activity, and liver injury monitoring in a carbon tetrachloride (CCl₄)-induced rat model.

Methods

Model rats from CCl₄-induced liver fibrosis (fibrosis group: n = 41; regression group: n = 20) and control (n = 11) groups underwent black blood T1rho magnetic resonance (MR) imaging (MRI). Injection of CCl₄ was done twice weekly for up to 12 weeks in the fibrosis group and for up to 6 weeks in the regression group. MR scanning time points were at baseline and at 2, 4, 6, 8, 10 and 12 weeks after CCl₄ injection in the fibrosis group and at baseline and at 2, 4, 6 (CCl₄ withdrawal), 7, 8, 10 and 12 weeks in the regression group.

Results

In the fibrosis group, liver T1rho values increased gradually within week 8 and then decreased. In the regression group, T1rho values dropped gradually after the withdrawal of CCl₄ and fell below those at baseline. The T1rho values at S0 were lower than those at any other stage (all P < 0.05). The T1rho values at G0 were significantly lower than those at any other grade, and G1 was lower than G2 (all P < 0.01). The T1rho values mildly correlated with fibrosis stages (r = 0.362) and moderately correlated with grades of inflammation (r = 0.568). The T1rho values of rats with the same inflammation grades showed no significant difference among different fibrosis stages, and the T1rho values at S3 showed a significant difference among different grades of inflammation (P = 0.024). Inflammation grade was an independent variable associated with T1rho values (P < 0.001).

Conclusion

T1rho MRI can be used to monitor CCl₄-induced liver injury, and inflammatory activity had a greater impact on liver T1rho values than fibrosis.

Clinical and Preclinical Imaging of Hepatosplenic Schistosomiasis

Schistosomiasis, a neglected tropical disease, is a major cause of chronic morbidity and disability, and premature death. The hepatosplenic form of schistosomiasis is characterized by hepatosplenomegaly, liver fibrosis, portal hypertension, and esophageal varices, whose rupture may cause bleeding and death. We review currently available abdominal imaging modalities and describe their basic principles, strengths, weaknesses, and usefulness in the assessment of hepatosplenic schistosomiasis (HSS). Advanced imaging methods are presented that could be of interest for hepatosplenic schistosomiasis evaluation by yielding morphological, functional, and molecular parameters of disease progression. We also provide a comprehensive view of preclinical imaging studies and current research objectives such as parasite visualization in hosts, follow-up of the host's immune response, and development of noninvasive quantitative methods for liver fibrosis assessment.

Quantification of Hemodynamic Changes in Chronic Liver Disease: Correlation of Perfusion-CT Data with Histopathologic Staging of Fibrosis

RATIONALE AND OBJECTIVES

To noninvasively estimate the severity of liver fibrosis using perfusion-CT (PCT)-based quantification of dual liver blood supply prior to liver transplantation or liver resections and to correlate results with histological grading of fibrosis stages and AST-platelet ratio index.

MATERIALS AND METHODS

Institutional review board approved this retrospective study. We analysed 41 consecutive patients (19 classified as Child-Pugh A, 17 as Child-Pugh B, and 5 as Child-Pugh C; MELD score ranged from 7 to 28) who underwent PCT prior to liver transplantation/liver resections between 2013 and 2016. The examination protocol included a scan time of 40 s, 80 kV, 100/120 mAs. Arterial liver perfusion, portal-venous perfusion and hepatic perfusion index (HPI) were registered in liver parenchyma by three readers. Fibrosis was histological graded according to Ishak scoring system as liver fibrosis (F3, n = 10), incomplete liver cirrhosis (F5, n = 5), and complete liver cirrhosis (F6, n = 26).

RESULTS

Portal-venous perfusion was significantly higher in liver fibrosis (F3 69.5±23.7 ml/100 ml/min) compared to incomplete liver cirrhosis (F5, 52.9±25.7 ml/100 ml/min) and complete liver cirrhosis (F6, 46.4±24.8 ml/100 ml/min (range 6.3-112.0 ml/100 ml/min; F = 15, p < 0.0001). HPI showed the same group differences (F = 20, p < 0.0001; HPI F3: 19.1±10.7%, HPI F5: 38.5±24.3%, HPI F6: 43.4±25.8%). Group comparisons were not significant for arterial liver perfusion (F = 3, p = 0.15). PCT parameters as well as histological fibrosis grading did neither correlate with laboratory findings including AST-platelet ratio index and MELD-Score, nor with Child-Pugh-Score.

CONCLUSION

Quantitative data from perfusion-CT can be used to differentiate between liver fibrosis (F3) and liver cirrhosis (F5/F6).

A novel STAT3 inhibitor, STX-0119, attenuates liver fibrosis by inactivating hepatic stellate cells in mice

Liver fibrosis is characterized by formation of scar tissue in the liver. The role of STAT3 signaling has been implicated on activating hepatic stellate cells (HSC) to myofibroblast-like cells in liver fibrosis. Major factors that activate STAT3 signaling are TGF-β1 and IL-6, which are upregulated in the liver in patients afflicted with liver fibrosis. Recent reports indicate that not only IL-6, but also the non-canonical signaling pathway of TGF-β1 is associated with STAT3 signaling. In this study, we demonstrate a new function of the STAT3 inhibitor, STX-0119, in liver fibrosis. STX-0119 is an inhibitor of STAT3 dimerization, which is required for nuclear localization of STAT3. We first investigated the anti-fibrotic effect of STX-0119 in in vitro experiments. Exposure to STX-0119 inhibited the nuclear localization of STAT3 in HSCs, resulting in decreased expression of its target genes, such as col1a1 and αSMA. In addition, STX-0119 also inhibited the TGF-β1/IL-6-induced activation of HSCs. Next, we examined the in vivo effect of STX-0119 in the liver fibrosis mouse model using thioacetamide (TAA) and carbon tetrachloride (CCl₄). STX-0119 attenuated the TAA-induced liver fibrosis by inhibiting activation of HSCs to myofibroblast-like cells. Consistent with the in vivo results using TAA-induced liver fibrosis model, treatment of STX-0119 similarly attenuated CCl₄-induced liver fibrosis. In conclusion, we believe that STX-0119 inhibits the development of liver fibrosis by blocking the activation of hepatic stellate cells. These results indicate that STX-0119 is a potential new therapeutic strategy to prevent disease progression to cirrhosis.

Intravoxel incoherent motion derived liver perfusion/diffusion readouts can be reliable biomarker for the detection of viral hepatitis B induced liver fibrosis

BACKGROUND

Recent two studies reported that intravoxel incoherent motion (IVIM) analysis can separate healthy livers and viral hepatitis B (VHB) induced liver fibrosis. However, in these two studies the starting b value for bi-exponential decay analysis was b =10 and 15 s/mm2 respectively. The current study has two primary aims. The first is to further confirm the diagnostic value of IVIM in detecting liver fibrosis. The second is to test whether by sampling very low b value densely, then b =0 s/mm2 image could be included to improve IVIM's diagnostic performance.

METHODS

This was a prospective study with data acquired at the Third Xiangya Hospital of Central South University, Changsha, China. Healthy volunteers and patients suspected of VHB induced liver fibrosis with liver biopsy performed, as well as hepatocellular carcinoma patients scheduled for surgery, were recruited. All the hepatocellular carcinoma patients had liver fibrosis. After exclusions based on pre-defined criteria for image data quality, for IVIM analysis this study included 20 healthy volunteers; 4 chronic VHB patients with biopsy showing no liver fibrosis; 11 stage-1 liver fibrosis patients, 10 stage-2 liver fibrosis patients, 2 stage-3 liver fibrosis patients, and 5 stage-4 liver fibrosis patients. In the liver fibrosis patients, 1, 19, and 8 cases had inflammation grade-0, grade-1, and grade-2 respectively. The reference IVIM bi-exponential decay curve fitting analysis was segmented fitting performed with b =2 s/mm2 image as the starting point and a threshold-b of 60 s/mm2. This reference fitting method was compared with threshold-b of 40 s/mm2, full fitting, fitting starting from b =0, 5, and 10 s/mm2 respectively. The potential correlation between IVIM readouts and liver function was assessed for the liver fibrosis patients.

RESULTS

Based on the smaller coefficient of variation (CoV) for the volunteer group and the smaller patient/volunteer ratios [= (mean measurement for patient groups)/(mean measurement for healthy volunteers)], the comparison of fitting methods favored the reference approach starting from b =2 s/mm2 with a threshold-b of 60 s/mm2. The IVIM measures of four patients without liver fibrosis resembled those of healthy subjects. PF offered the best diagnostic value for separating healthy livers and fibrotic livers, and a threshold of PF =0.1406 separated all fibrotic livers and healthy livers with an exception of one hepatocellular carcinoma patient (fibrosis grade-2/inflammation grade-2). The correlation between fibrosis grading and inflammation grading was weakly positive; while compared with fibrotic livers with inflammation grade-1, fibrotic livers with inflammation grade-2 showed a trend of higher Dfast. A weak correlation is shown with lower PF and lower Dfast associated with lower total protein, lower albumin; higher alanine transaminase, higher aspartate transaminase; higher total bilirubin, and higher direct bilirubin.

CONCLUSIONS

Segmented-fitting with threshold-b =60 s/mm2 and starting from non-zero very low b value outperforms other methods. IVIM has high sensitivity in detecting liver fibrosis, and PF and Dfast have potential correlation with serum liver function biomarkers. IVIM measures and liver fibrosis grading are not in a linear relationship.

Hepatic blood flow by perfusion computed tomography as an imaging biomarker for patients with gastric cancer

Perfusion computed tomography (PCT) is a less invasive imaging modality that provides information about tissue hemodynamics at the capillary level. The present study aimed to investigate the correlation between hepatic perfusion and gastric cancer progression. A total of 136 patients with gastric adenocarcinoma were evaluated in the present study. Prior to initial treatment, liver PCT was performed across the hepatic hilar plane and the hepatic blood flow (HBF) was measured using the dual-input deconvolution method. HBF was compared with clinicopathological factors, patient prognosis and circulating serum proangiogenic cytokines. The median HBF was 217 ml/min/100 g tissue. Patients with high HBF had larger tumors (43 mm vs. 71, P<0.001) and more advanced tumor-node stages (P<0.001 for both). When both patient groups of operable and inoperable were compared by their respective median HBF values, each high-HBF group had a significantly worse prognosis (P=0.002 and P=0.024), notably in the inoperable group, with <1-year survival. In 17 postoperative recurrent patients, the high-HBF at recurrence group also had a significantly worse postrecurrent prognosis (P=0.019). HBF was an independent prognostic factor (hazard ratio, 2.019; P=0.048) and was strongly associated with serum vascular endothelial growth factor level (R=0.607, P<0.001). HBF was significantly correlated with gastric cancer progression, and is an easily measured imaging biomarker reflecting patient survival.

Diagnostic Performance of Shear Wave Elastography in Patients With Autoimmune Liver Disease

OBJECTIVES

To assess performance of shear wave elastography for evaluation of fibrosis and the histologic stage in patients with autoimmune liver disease (ALD) and to validate previously established advanced fibrosis cutoff values in this cohort.

METHODS

Shear wave elastography was performed on patients with ALD with an Aixplorer ultrasound system (SuperSonic Imagine, Aix-en-Provence, France) using an SC6-1 transducer. The median estimated tissue Young modulus was calculated from sets of 8 to 10 elastograms. A blinded, subspecialty-trained pathologist reviewed biopsy specimens. The METAVIR classification was used to stage liver fibrosis and necroinflammation. Steatosis was graded from 0 to 4+. The Kendall τ-b correlation test was performed to identify the correlation between the estimated tissue Young modulus and fibrosis, steatosis, and the necroinflammatory score. The Spearman correlation test was performed to identify the correlation between the estimated tissue Young modulus and clinical data. The diagnostic performance of shear wave elastography for differentiating METAVIR stage F2 or higher from F0 and F1 fibrosis was evaluated by a receiver operating characteristic (ROC) curve analysis.

RESULTS

Fifty-one patients with ALD were analyzed. The estimated tissue Young modulus was positively correlated with the fibrosis stage and necroinflammation score (r = 0.386; P < .001; r = 0.338; P = .002, respectively) but not steatosis (r = -0.091; P = .527). Serum aspartate aminotransferase, alanine aminotransferase, and total bilirubin values were positively correlated with the estimated tissue Young modulus (r = 0.501; P < .001; r = 0.44; P = .001; r = 0.291; P = .038). The serum albumin value was negatively correlated (r = -0.309; P = .033). The area under the ROC curve was 0.781 (95% confidence interval, 0.641-0.921) for distinguishing F2 or greater fibrosis from F0 and F1 fibrosis. Based on the ROC curve, an optimal cutoff value of 9.15 kPa was identified (sensitivity, 83.3%; specificity, 72.7%).

CONCLUSIONS

Shear wave elastography is a novel noninvasive adjunct to liver biopsy in evaluation and staging of patients with ALD, showing the potential for serial evaluations of disease progression and treatment responses.

Short-term changes observed in multiparametric liver MRI following therapy with direct-acting antivirals in chronic hepatitis C virus patients

Methods

We applied multiparametric MRI to assess changes in liver composition, perfusion and blood flow in 17 patients before direct-acting antiviral (DAA) therapy and after treatment completion (within 12 weeks of last DAA tablet swallowed).

Results

We observed changes in hepatic composition indicated by a reduction in both liver longitudinal relaxation time (T1, 35 ± 4 ms), transverse relaxation time (T2, 2.5 ± 0.8 ms; T2* 3.0 ± 0.7 ms), and liver perfusion (28.1 ± 19.7 ml/100 g/min) which we suggest are linked to reduced pro-inflammatory milieu, including interstitial oedema, within the liver. No changes were observed in liver or spleen blood flow, splenic perfusion, or superior mesenteric artery blood flow.

Conclusion

For the first time, our study has shown that treatment of HCV with DAAs in patients with cirrhosis leads to an acute reduction in liver T1, T2 and T2* and an increase in liver perfusion measured using MR parameters. The ability of MRI to characterise changes in the angio-architecture of patients with cirrhosis after intervention in the short term will enhance our understanding of the natural history of regression of liver disease and potentially influence clinical decision algorithms.

Key Points

• DAAs have revolutionised the treatment of hepatitis C and achieve sustained virological response in over 95% of patients, even with liver cirrhosis.

• Currently available non-invasive measures of liver fibrosis are not accurate after HCV treatment with DAAs, this prospective single-centre study has shown that MRI can sensitively measure changes within the liver, which could reflect the reduction in inflammation with viral clearance.

• The ability of MRI to characterise changes in structural and haemodynamic MRI measures in the liver after intervention will enhance our understanding of the progression/regression of liver disease and could potentially influence clinical decision algorithms.

Compartment model analysis of intravenous contrast-enhanced dynamic computed tomography in hepatic hemodynamics: A validation study using intra-arterial contrast-enhanced computed tomography

AIM

To verify the utility of the 2-in-1-out-compartment model analysis (CMA) of intravenous contrast-enhanced dynamic computed tomography (IV-CT) for evaluating hepatic arterial and portal venous flow using intra-arterial contrast-enhanced CT (IA-CT).

METHODS

We retrospectively evaluated 49 consecutive patients who underwent IV-CT and were radiologically or histologically diagnosed as having hepatic malignant lesion (51 classical hepatocellular carcinomas [HCC], 4 early HCC, 3 cholangiolocellular carcinomas, 1 mixed HCC, 3 cholangiocellular carcinomas). As a gold standard for hepatic arterial and portal blood flows, we defined the normalized enhancement in CT values on CTAP (nCTAP) and CTHA (nCTHA). The hepatic arterial (k_1a ) and portal venous inflow velocity (k_1p ) constants in hepatic lesions and surrounding liver parenchyma were obtained from the CMA of IV-CT with various outflow velocity constant (k₂ ) limits using the nonlinear least square method. The correlation coefficient between the normalized enhancement in IA-CT and CMA of IV-CT was statistically evaluated according to various k₂ limits.

RESULTS

The highest mean correlation coefficient between k_1a and nCTHA (r = 0.65, P < 0.0001) was observed when k₂ ≦0.035. The highest mean correlation coefficient between k_1p and nCTAP (r = 0.69, P < 0.0001) was observed when k₂ ≦0.045. The decrease in correlation coefficient was significant when the upper k₂ limit was lower than 0.03 or higher than 0.07 compared to the best mean correlation coefficient (P < 0.05).

CONCLUSION

Hepatic arterial and portal venous flows can be evaluated quantitatively to some extent with appropriate outflow velocity constant limits using the CMA of IV-CT.

Multidetector Computed Tomography for Retrospective, Noninvasive Staging of Liver Fibrosis

Although not traditionally used to assess hepatic fibrosis, computed tomography (CT) is fast, accessible, robust, and commonly used for abdominal indications. CT metrics are often easily retrospectively obtained without special equipment. Metrics such as liver segmental volume ratio, which quantifies regional hepatic volume changes; splenic volume; and liver surface nodularity scoring show diagnostic performance comparable to elastography techniques for detecting significant and advanced fibrosis. Other emerging CT tools, such as CT texture analysis and fractional extracellular volume, have also shown promise in identifying fibrosis and warrant further study.

CT predicts liver fibrosis: Prospective evaluation of morphology- and attenuation-based quantitative scores in routine portal venous abdominal scans

Objectives

Our aim was to prospectively determine whether quantitative computed tomography (CT) scores, consisting of simplified indices for liver remodeling and attenuation, may predict liver fibrosis in abdominal CT scans.

Materials and methods

This cross-sectional, prospective study was approved by the local IRB (Kantonale Ethikkommission Bern). Written informed consent was given from all patients undergoing study-MR exams. Between 02/16 and 05/17, four different liver fibrosis scores (CRL-R = caudate-right-lobe ratio, LIMV-, LIMA- and LIMVA-fibrosis score, with “LIM” for liver imaging morphology, “V” for liver vein diameter and “A” for attenuation) were calculated in 1534 consecutive abdominal CT scans, excluding patients with prior liver surgery and liver metastasis. Patients were invited to undergo magnetic resonance (MR) elastography as the non-invasive gold standard to evaluate liver fibrosis. MR elastography shear modulus ≥2.8 kPa was defined as beginning liver fibrosis, while ≥3.5 kPa was defined as significant liver fibrosis (which would correspond to fibrosis stage F2 or higher in histology). Cutoff values, sensitivities and specificities obtained from the receiver operating characteristics (ROC) analysis were then calculated in 141 patients who followed the invitation for MR elastography. To mitigate selection bias, prevalence was estimated in the screened total population (n = 1534) by applying the cutoff values with sensitivities and specificities calculated in the MR elastography sub-group. Positive predictive values (PPV) and negative predictive values (NPV) were then calculated.

Results

Fibrosis scores including liver vein attenuation LIMA-FS and LIMVA-FS showed higher areas under the ROC curves (0.96–0.97) than CRL-R (0.82) to detect significant liver fibrosis, while LIMV-FS showed good performance as well (0.92). The prevalence-corrected PPV were 29% for CRL-R, 70% for LIMV-FS, 76% for LIMA-FS and 82% for LIMVA-FS.

Conclusion

CT fibrosis scores, notably LIMA-FS and LIMVA-FS, may predict significant liver fibrosis on routine abdominal CT scans.

Investigation of the values of CT perfusion imaging and ultrasound elastography in the diagnosis of liver fibrosis

This study intended to investigate the clinical application values of computed tomography (CT) perfusion imaging and ultrasound elastography in the diagnosis of liver fibrosis, and to analyze the characteristics and diagnostic values of the two methods in liver fibrosis. A total of 320 patients diagnosed with suspected liver fibrosis in Qingdao Municipal Hospital from April 2014 to May 2016 were selected. The patients were diagnosed by ultrasound elastography and CT perfusion imaging, respectively, and the influencing characteristics and diagnostic accuracies of the two methods were compared. Among 320 patients, there were 315 definitely diagnosed with liver fibrosis through liver biopsy. The accuracy of CT perfusion imaging was 95.63% (306/325), while that of ultrasound elastography was 91.88% (294/320); there was a significant difference in accuracy between the two methods (P>0.05). CT perfusion imaging was superior to ultrasound elastography in the degree of liver fibrosis (P<0.05). Receiver operating characteristic (ROC) curve analysis showed that the areas under the curve (AUC) of patients were 0.841 and 0.865 in S1 (P>0.05), 0.830 and 0.887 in S2 (P>0.05), 0.851 and 0.931 in S3 (P>0.05), and 0.951 and 0.970 in S4, respectively (P>0.05). AUC values of ROC curves of CT perfusion imaging and ultrasound elastography in diagnosing liver fibrosis were 0.833 and 0.857, respectively (P>0.05). Both CT perfusion imaging and ultrasound elastography have relatively high accuracies in the clinical diagnosis of liver fibrosis, and they are worth promoting and applying. However, the best imaging method needs to be selected according to the actual situation of patients and research purpose.

Accuracy and precision of quantitative DCE-MRI parameters: How should one estimate contrast concentration?

INTRODUCTION

Pharmacokinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) data are sensitive to acquisition and post-processing techniques, which makes it difficult to compare results obtained using different methods. In particular, one of the most important factors affecting estimation of model parameters is how to convert MRI signal intensities to contrast agent concentration. The purpose of our study was to quantitatively compare a linear signal-to-concentration conversion (LC) as an approximation and a non-linear conversion (NLC) based on the MRI signal equation, in terms of the accuracy and precision of the pharmacokinetic parameters in T₁-weighted DCE-MRI.

MATERIALS AND METHODS

Numerical simulation studies were conducted to compare LC and NLC in terms of the accuracy and precision in contrast kinetic parameter estimation, and to evaluate their dependency on flip angle (FA), pre-contrast T₁ (T₁₀) and arterial input function (AIF). In addition, the effect of the conversion method on the diagnostic accuracy was evaluated with 36 breast lesions (19 benign and 17 malignant).

RESULTS

The transfer rate (K^trans) estimated using LC and measured AIF (mAIF) were up to 38% higher than the true K^trans values, while the LC K^trans estimates with the presumed AIF (pAIF) were up to 7% lower than the true K^trans values, when FA = 45°. When using a small FA, such as 12°, the LC K^trans with pAIF had least sensitivity to the error in T₁₀ compared to the K^trans estimated using LC with mAIF, and NLC with pAIF or mAIF. The breast DCE-MRI study showed that both LC and NLC K^trans were significantly different (p < 0.05) between the malignant and benign lesions. The effect size between benign and malignant values as measured by Cohen's d was 1.06 for LC K^trans and 1.02 for NLC K^trans.

CONCLUSION

The present study results show that, when precontrast T₁ measurement is not available and a low FA is used for DCE-MRI, the uncertainty in the contrast kinetic parameter estimation can be reduced by using the LC method with pAIF, without compromising the diagnostic accuracy.

Assessment of liver fibrosis by ultrasound elastography and contrast-enhanced ultrasound: a randomized prospective animal study

This study aimed to assess liver fibrosis by contrast-enhanced ultrasound (CEUS) and point shear-wave elastography (pSWE) in rabbits and compare the performance of the two techniques. Eighty rabbits were divided into experimental (n=60) and control group (n=20). In the experimental group, liver fibrosis (F1-F4) was induced by subcutaneous injection of carbon tetrachloride. CEUS and pSWE of the liver was performed for the two groups at a 4-week interval for 40 weeks. The portal vein rise time (PV-RT), time to peak (PV-TTP), mean transit time (PV-MTT) and the maximum signal intensity (PV-Imax) were analyzed with time-intensity curves (TICs). Liver stiffness value (LSV) was obtained through pSWE. Histologic examination of liver specimens of the rabbits was performed to evaluate the fibrosis stage. PV-RT, PV-TTP, PV-Imax and LSV were significantly different among five liver fibrosis stages (F0-F4) (P<0.01). PV-Imax and LSV displayed better diagnostic performance than PV-RT, PV-TTP, PV-MTT. For diagnosing≥F1 stage fibrosis, the area under the receiver operating characteristic curve (AUROC) of PV-Imax was 0.870, which was similar to that of LSV 0.874 (P=0.94). For diagnosing ≥F2, ≥F3 and ≥F4 stage fibrosis, the AUROC of PV-Imax and LSV was 0.845 vs. 0.956 (P=0.04), 0.789 vs. 0.954 (P=0.01) and 0.707 vs. 0.933 (P=0.03). Both CEUS and pSWE had the potential to be complementary imaging tools in the evaluation of liver fibrosis. The performance of pSWE may be better than CEUS.

Imaging of nonalcoholic fatty liver disease and its clinical utility

The prevalence of nonalcoholic fatty liver disease has been continuously rising over the last three decades and is projected to become the most common indication for liver transplantation in the near future. Its pathophysiology and complex interplay with diabetes and the metabolic syndrome are not as yet fully understood despite growing scientific interest and research. Modern imaging techniques offer significant assistance in this field by enabling the study of the liver noninvasively and evaluation of the degree of both steatosis and fibrosis, and even in attempting to diagnose the presence of inflammation (steatohepatitis). The derived measurements are highly precise, accurate and reproducible, performing better than biopsy in terms of quantification. In this article, these imaging techniques are overviewed and their performance regarding diagnosis, stratification and monitoring are evaluated. Their expanding role both in the research arena and in clinical practice along with their limitations is also discussed.

Evaluation of splenic perfusion and spleen size using dynamic computed tomography: Usefulness in assessing degree of liver fibrosis

AIM

To enhance the usefulness of splenic perfusion evaluated by means of dynamic computed tomography (CT) and spleen size in assessing the degree of liver fibrosis.

METHODS

We retrospectively studied 133 patients who had undergone dynamic CT before hepatectomy. Fibrosis was histologically established in all. First we calculated splenic perfusion parameters K₁ (inflow rate constant), 1/k₂ (mean transit time; MTT), and K₁ /k₂ (distribution volume; V_d ), using compartment model analysis. Then we compared the stage of fibrosis with splenic perfusion and spleen size (long axis, R), using the Kruskal-Wallis test and multiple comparisons. After that, we assessed the diagnostic accuracy of the combination of splenic perfusion, spleen size, age, gender, and the presence or absence of hepatitis B and hepatitis C viral infection in detecting liver fibrosis, using stepwise regression and receiver operating characteristic analysis.

RESULTS

Significant differences (P < 0.05) in MTT were observed in comparisons between fibrosis stages F0 and F4, between F1 and F4, and between F2 and F4. Significant differences (P < 0.05) in R were observed in comparisons between F0 and F4, and between F1 and F4. Considering the presence or absence of hepatitis B and C viral infection along with MTT and R, the areas under the receiver operating characteristic curves were 0.89 for ≥F1, 0.83 for ≥F2, 0.82 for ≥F3, and 0.82 for F4.

CONCLUSION

Splenic MTT and spleen size are helpful in assessing liver fibrosis.

Multi-detector CT: Liver protocol and recent developments

Multi-detector computed tomography is today the workhorse in the evaluation of the vast majority of patients with known or suspected liver disease. Reasons for that include widespread availability, robustness and repeatability of the technique, time-efficient image acquisitions of large body volumes, high temporal and spatial resolution as well as multiple post-processing capabilities. However, as the technique employs ionizing radiation and intravenous iodine-based contrast media, the associated potential risks have to be taken into account. In this review article, liver protocols in clinical practice are discussed with emphasis on optimisation strategies. Furthermore, recent developments such as perfusion CT and dual-energy CT and their applications are presented.

Impact of Liver Fibrosis and Fatty Liver on T1rho Measurements: A Prospective Study

OBJECTIVE

To investigate the liver T1rho values for detecting fibrosis, and the potential impact of fatty liver on T1rho measurements.

MATERIALS AND METHODS

This study included 18 healthy subjects, 18 patients with fatty liver, and 18 patients with liver fibrosis, who underwent T1rho MRI and mDIXON collections. Liver T1rho, proton density fat fraction (PDFF) and T2* values were measured and compared among the three groups. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the T1rho values for detecting liver fibrosis. Liver T1rho values were correlated with PDFF, T2* values and clinical data.

RESULTS

Liver T1rho and PDFF values were significantly different (p < 0.001), whereas the T2* (p = 0.766) values were similar, among the three groups. Mean liver T1rho values in the fibrotic group (52.6 ± 6.8 ms) were significantly higher than those of healthy subjects (44.9 ± 2.8 ms, p < 0.001) and fatty liver group (45.0 ± 3.5 ms, p < 0.001). Mean liver T1rho values were similar between healthy subjects and fatty liver group (p = 0.999). PDFF values in the fatty liver group (16.07 ± 10.59%) were significantly higher than those of healthy subjects (1.43 ± 1.36%, p < 0.001) and fibrosis group (1.07 ± 1.06%, p < 0.001). PDFF values were similar in healthy subjects and fibrosis group (p = 0.984). Mean T1rho values performed well to detect fibrosis at a threshold of 49.5 ms (area under the ROC curve, 0.855), had a moderate correlation with liver stiffness (r = 0.671, p = 0.012), and no correlation with PDFF, T2* values, subject age, or body mass index (p > 0.05).

CONCLUSION

T1rho MRI is useful for noninvasive detection of liver fibrosis, and may not be affected with the presence of fatty liver.

Evaluation of hepatic fibrosis: a review from the society of abdominal radiology disease focus panel

Hepatic fibrosis is potentially reversible; however early diagnosis is necessary for treatment in order to halt progression to cirrhosis and development of complications including portal hypertension and hepatocellular carcinoma. Morphologic signs of cirrhosis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) alone are unreliable and are seen with more advanced disease. Newer imaging techniques to diagnose liver fibrosis are reliable and accurate, and include magnetic resonance elastography and US elastography (one-dimensional transient elastography and point shear wave elastography or acoustic radiation force impulse imaging). Research is ongoing with multiple other techniques for the noninvasive diagnosis of hepatic fibrosis, including MRI with diffusion-weighted imaging, hepatobiliary contrast enhancement, and perfusion; CT using perfusion, fractional extracellular space techniques, and dual-energy, contrast-enhanced US, texture analysis in multiple modalities, quantitative mapping, and direct molecular imaging probes. Efforts to advance the noninvasive imaging assessment of hepatic fibrosis will facilitate earlier diagnosis and improve patient monitoring with the goal of preventing the progression to cirrhosis and its complications.

Validation of Shear Wave Elastography Cutoff Values on the Supersonic Aixplorer for Practical Clinical Use in Liver Fibrosis Staging

The purpose of this study was to determine the validity of previously established ultrasound shear wave elastography (SWE) cut-off values (≥F2 fibrosis) on an independent cohort of patients with chronic liver disease. In this cross-sectional study, approved by the institutional review board and compliant with the Health Insurance Portability and Accountability Act, 338 patients undergoing liver biopsy underwent SWE using an Aixplorer ultrasound machine (SuperSonic Imagine, Aix-en-Provence, France). Median SWE values were calculated from sets of 10 elastograms. A single blinded pathologist evaluated METAVIR fibrosis staging as the gold standard. The study analyzed 277 patients with a mean age of 48 y. On pathologic examination, 212 patients (76.5%) had F0-F1 fibrosis, whereas 65 (23.5%) had ≥F2 fibrosis. Spearman's correlation of fibrosis with SWE was 0.456 (p < 0.001). A cut-off value of 7.29 kPa yielded sensitivity of 95.4% and specificity of 50.5% for the diagnosis of METAVIR stage ≥F2 liver fibrosis in patients with liver disease using the SuperSonic Imagine Aixplorer SWE system.

Material Separation Using Dual-Energy CT: Current and Emerging Applications

Dual-energy (DE) computed tomography (CT) offers the opportunity to generate material-specific images on the basis of the atomic number Z and the unique mass attenuation coefficient of a particular material at different x-ray energies. Material-specific images provide qualitative and quantitative information about tissue composition and contrast media distribution. The most significant contribution of DE CT-based material characterization comes from the capability to assess iodine distribution through the creation of an image that exclusively shows iodine. These iodine-specific images increase tissue contrast and amplify subtle differences in attenuation between normal and abnormal tissues, improving lesion detection and characterization in the abdomen. In addition, DE CT enables computational removal of iodine influence from a CT image, generating virtual noncontrast images. Several additional materials, including calcium, fat, and uric acid, can be separated, permitting imaging assessment of metabolic imbalances, elemental deficiencies, and abnormal deposition of materials within tissues. The ability to obtain material-specific images from a single, contrast-enhanced CT acquisition can complement the anatomic knowledge with functional information, and may be used to reduce the radiation dose by decreasing the number of phases in a multiphasic CT examination. DE CT also enables generation of energy-specific and virtual monochromatic images. Clinical applications of DE CT leverage both material-specific images and virtual monochromatic images to expand the current role of CT and overcome several limitations of single-energy CT. (©)RSNA, 2016.

Diminished liver microperfusion in Fontan patients: A biexponential DWI study

It has been demonstrated that hepatic apparent diffusion coefficients (ADC) are decreasing in patients with a Fontan circulation. It remains however unclear whether this is a true decrease of molecular diffusion, or rather reflects decreased microperfusion due to decreased portal blood flow. The purpose of this study was therefore to differentiate diffusion and microperfusion using intravoxel incoherent motion (IVIM) modeled diffusion-weighted imaging (DWI) for different liver segments in patients with a Fontan circulation, compare to a control group, and relate with liver function, chronic hepatic congestion and hepatic disease. For that purpose, livers of 59 consecutively included patients with Fontan circulation (29 men; mean-age, 19.1 years) were examined (Oct 2012─Dec 2013) with 1.5T MRI and DWI (b = 0,50,100,250,500,750,1500,1750 s/mm²). IVIM (D_slow, D_fast, f_fast) and ADC were calculated for eight liver segments, compared to a control group (19 volunteers; 10 men; mean-age, 32.9 years), and correlated to follow-up duration, clinical variables, and laboratory measurements associated with liver function. The results demonstrated that microperfusion was reduced (p<0.001) in Fontan livers compared to controls with ─38.1% for D_fast and ─32.6% for f_fast. Molecular diffusion (D_slow) was similar between patients and controls, while ADC was significantly lower (─14.3%) in patients (p<0.001). ADC decreased significantly with follow-up duration after Fontan operation (r = ─0.657). D_slow showed significant inverse correlations (r = ─0.591) with follow-up duration whereas D_fast and f_fast did not. From these results it was concluded that the decreasing ADC values in Fontan livers compared with controls reflect decreases in hepatic microperfusion rather than any change in molecular diffusion. However, with the time elapsed since the Fontan operation molecular diffusion and ADC decreased while microperfusion remained stable. This indicates that after Fontan operation initial blood flow effects on the liver are followed by intracellular changes preceding the formation of fibrosis and cirrhosis.

Liver volume is a prognostic indicator for clinical outcome of patients with alcoholic hepatitis

PURPOSE

To evaluate the prognostic value of abdominal computed tomography (CT) in patients with alcoholic hepatitis (AH).

METHODS

This ancillary study was based on data collected during a previous randomized controlled trial in patients with AH. Clinical response was defined as the improvement of the baseline MELD score ≥3 points at 3 months. All patients underwent contrast-enhanced CT of the abdomen. The following parameters were measured: (1) liver density, spleen density, and liver-to-spleen density ratio; (2) liver-to-body weight (LBW) ratio; and (3) subcutaneous fat, visceral fat, and muscular content. Improvers and non-improvers were compared with univariate, multivariate, and ROC analyses. Results were compared with a validation cohort of patients.

RESULTS

Fifty-eight patients (mean age, 56 years) were analyzed, including 34 (59 %) improvers. On multivariate analysis, LBW ratio (OR = 3.73; 95 % CI, 1.65-8.46; p = 0.002) and subcutaneous fat (OR = 1.01; 95 % CI, 1.00-1.02; p = 0.022) were associated with clinical response, with AUROC curves of 0.78 ± 0.06 (p < 0.001) and 0.66 ± 0.07 (p = 0.043), respectively. LBW ≥2.4 % predicted response with 88 % sensitivity and 63 % specificity. In the validation cohort (n = 42, 64 % improvers), the same cut-off value predicted response with 93 % sensitivity and 60 % specificity.

CONCLUSIONS

In patients suffering from AH, the liver volume appears to be a major positive prognostic factor.

Non-invasive diagnosis of hepatitis B virus-related cirrhosis

Chronic hepatitis B (CHB)-related cirrhosis is a major threat to public health, and about 23% of patients with CHB progress naturally to liver cirrhosis. Worldwide, about 650000 people die each year from various complications caused by CHB. liver cirrhosis has become a global concern. Progressive hepatic fibrosis can lead to cirrhosis, and early diagnosis of liver fibrosis is fundamental. Staging fibrosis is critical for the prognosis evaluation and management of patients with liver diseases. Liver biopsy is the reference standard for assessment of liver fibrosis. However, this method is invasive, and is associated with pain and complications that can be fatal, which leads to the progress of non-invasive assessment based on serological and imaging techniques. These non-invasive assessments have been shown to be effective in the diagnosis of liver fibrosis. This article mainly introduces the principle, clinical application, diagnostic efficacy, and limitations of non-invasive assessments for hepatitis B virus-related fibrosis.

Contrast-enhanced ultrasound and computerized tomography perfusion imaging of a liver fibrosis-early cirrhosis in dogs

BACKGROUND AND AIM

To assess liver fibrosis stages in a liver fibrosis-early cirrhosis model in dogs, the clinical efficiency of contrast-enhanced ultrasound (CEUS) and computed tomography (CT) perfusion imaging were compared.

METHODS

Hepatic vein arriving time (HVAT), hepatic artery arriving time, and hepatic artery to vein transit time (HA-VTT) were measured on CEUS. Total liver perfusion (TLP), portal vein perfusion (PVP), hepatic artery perfusion, and hepatic perfusion index (HPI) were measured on CT perfusion imaging. Histologic examination of liver specimens of the animals was performed to assess the fibrosis stage.

RESULTS

For assessment of liver fibrosis, the area under the receiver operating characteristic curve of CEUS indexes HVAT and HA-VTT were 0.865 and 0.930, respectively; the perfusion CT indexes TLP, PVP, and HPI were 0.797, 0.800, and 0.220, respectively; the serological index hyaluronic acid was 0.793. While for assessment of early cirrhosis, the area under the receiver operating characteristic curve of CEUS indexes HVAT and HA-VTT were 0.915 and 0.948, respectively; the perfusion CT indexes TLP, PVP, and HPI were 0.737, 0.765, and 0.218, respectively; the serological index hyaluronic acid was 0.627.

CONCLUSIONS

This study showed that both CEUS and CT perfusion imaging have the potential to be complementary imaging tools in the evaluation of liver fibrosis. While CEUS is the better choice and the index HA-VTT can be considered as non-invasive semi-quantitative indexes for diagnosing liver fibrosis and early cirrhosis.

Noninvasive models for assessment of liver fibrosis in patients with chronic hepatitis B virus infection

There are approximately 240 million patients with chronic hepatitis B virus (HBV) infection worldwide. Up to 40% of HBV-infected patients can progress to liver cirrhosis, hepatocellular carcinoma or chronic end-stage liver disease during their lifetime. This, in turn, is responsible for around 650000 deaths annually worldwide. Repeated hepatitis flares may increase the progression of liver fibrosis, making the accurate diagnosis of the stage of liver fibrosis critical in order to make antiviral therapeutic decisions for HBV-infected patients. Liver biopsy remains the "gold standard" for diagnosing liver fibrosis. However, this technique has recently been challenged by the development of several novel noninvasive tests to evaluate liver fibrosis, including serum markers, combined models and imaging techniques. In addition, the cost and accessibility of imaging techniques have been suggested as additional limitations for invasive assessment of liver fibrosis in developing countries. Therefore, a noninvasive assessment model has been suggested to evaluate liver fibrosis, specifically in HBV-infected patients, owing to its high applicability, inter-laboratory reproducibility, wide availability for repeated assays and reasonable cost. The current review aims to present the status of knowledge in this new and exciting field, and to highlight the key points in HBV-infected patients for clinicians.